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Researchers at the University of Nebraska Medical Center have recently published an article in the Journal of Occupational and Environmental Hygiene demonstrating the benefits of Lumacept UV-C reflective coatings. This study was conducted in the Nebraska Biocontainment Unit, which is one of only a few units in the US capable of treating patients with deadly infectious diseases such as Ebola. In this study, researchers used a portable UV device to inactivate MRSA and VRE and found that “coating hospital room walls with UV-reflective paint enhanced UVGI disinfection of nosocomial bacteria on various surfaces compared to standard paint, particularly at a surface placement site indirectly exposed to UVC light.”

In an article recently published in the Journal of Occupational and Environmental Hygiene, researchers at the CDC’s National Institute of Occupational Health and Safety studied the use of UVGI in an ambulance. The study found that optimizing the location of the UV fixtures and using Lumacept UV-C reflective paint “can substantially improve the performance of a UVGI system and reduce the time required for disinfection”. These finding are in excellent agreement with our previous trials of Lumacept in hospital rooms.

Abstract

Ambulances are frequently contaminated with infectious microorganisms shed by patients during transport that can be transferred to subsequent patients and emergency medical service workers. Manual decontamination is tedious and time-consuming, and persistent contamination is common even after cleaning. Ultraviolet germicidal irradiation (UVGI) has been proposed as a terminal disinfection method for ambulance patient compartments. However, no published studies have tested the use of UVGI in ambulances. The objectives of this study were to investigate the efficacy of a UVGI system in an ambulance patient compartment and to examine the impact of UVGI fixture position and the UV reflectivity of interior surfaces on the time required for disinfection. A UVGI fixture was placed in the front, middle or back of an ambulance patient compartment, and the UV irradiance was measured at 49 locations. Aluminum sheets and UV-reflective paint were added to examine the effects of increasing surface reflectivity on disinfection time. Disinfection tests were conducted using Bacillus subtilis spores as a surrogate for pathogens. Our results showed that the UV irradiance varied considerably depending upon the surface location. For example, with the UVGI fixture in the back position and without the addition of UV-reflective surfaces, the most irradiated location received a dose of UVGI sufficient for disinfection in 16 seconds, but the least irradiated location required 15 hours. Because the overall time required to disinfect all of the interior surfaces is determined by the time required to disinfect the surfaces receiving the lowest irradiation levels, the patient compartment disinfection times for different UVGI configurations ranged from 16.5 hours to 59 minutes depending upon the UVGI fixture position and the interior surface reflectivity. These results indicate that UVGI systems can reduce microbial surface contamination in ambulance compartments, but the systems must be rigorously validated before deployment. Optimizing the UVGI fixture position and increasing the UV reflectivity of the interior surfaces can substantially improve the performance of a UVGI system and reduce the time required for disinfection.

Previously, we wrote about how to “see” UV-C reflection or absorption. We’ve found that UV imaging can help us visualize how UV is scattered around a hospital room and, therefore, better understand which areas are being properly treated (and which may not be). While this is certainly useful, what we really need to know is the actual UV intensity on a given surface. In other words, how much UV light energy per square centimeter is hitting every surface in a room? This is the value that truly determines how much disinfection takes place. Scientists long ago correlated UV energy per area to germicidal performance, often expressed as log reduction.

UV intensity can be measured in a few different ways. Here we’ll discuss two: radiometric sensors and photochromic indicators.

Radiometric Sensors

Simply put, a radiometric sensor measures electromagnetic radiation. In our case, we are interested in the relatively narrow UV-C portion of the electromagnetic spectrum. Ideally, our sensor responds to UV-C wavelengths and ignores everything else. For example, we don’t care about the intensity of visible light, since those wavelengths are not germicidal. What is normally done is to add a filter that blocks out any wavelengths that we are not interested in.

Because germicidal irradiation is so prevalent in other industries, several companies make systems to measure UV-C intensity (usually referred to as “irradiance”). Normally, these consist of a sensor combined with a meter which converts the output from the sensor to a numerical value for irradiance in energy per area per time (e.g. Joules per square centimeter per second) . Below is the ILT1700 from International Light Technologies, which is the meter we use for most of our measurements.

The sensor can be placed anywhere in the room and the results used to map out the UV distribution. It is especially important to understand how much UV is hitting areas that are not in direct line of sight of the device. In our experience, most surfaces that can see the device will get adequately disinfected in a few minutes. It is the shadowed areas that truly dictate how long a given device should run, but, unfortunately, most device manufacturers ignore this fact.

Photochromic indicators

A less exact, but simpler, method is to use a photochromic indicator. These typically are small adhesive labels containing special pigments that change color as they are exposed to UV. For example, they may change from an initial yellow color to a dark green. In the case of a product called Spectrify from Spectra254, the label is initially white and gradually turns to a dark pink color. The darker the color, the greater the UV exposure. Calibration standards have been created to show how the color corresponds to a particular level of exposure.

The advantage of this approach is that the labels are relatively inexpensive, so numerous labels can be placed around the room to measure UV in many locations simultaneously. The information received is only semi-quantitative, but, nonetheless, provides valuable insight into which areas of the room are being properly disinfected. Also, because of their size, these labels can be put into tight spaces in which a radiometric sensor may not fit.

The importance of UV measurements

UV device effectiveness data provided by manufacturers typically only includes surfaces that are directly illuminated by the device. This ignores the large number of surfaces that are illuminated only indirectly, or are completely shadowed. To understand the entire picture and to establish a more effective device cycle time, it is necessary to take additional measurements of these indirect surfaces.

However, we can’t ignore an important variable- the location of the device in the room. Changing the device location slightly may significantly change the UV dosage on some surfaces, as they move in or out of shadows. An important benefit of Lumacept is that the diffuse reflectance of the paint helps make the dependence on the device location less significant by providing much more indirect light and essentially “smoothing” out these differences.

To properly optimize the device location, many UV intensity measurements must be taken while systematically moving the device. This can be time intensive and tedious, which is why we developed LumaSim. Through computer simulations, we can take thousands of virtual measurements and easily study the effect of adjusting the device location until the best location is found. The combination of Lumacept coatings and an optimized device location can not only make your disinfection protocol more effective, it can also save significant time.

Have any technical or not-so-technical questions about UV? We’re happy to help.Contact us atinfo@lumacept.com.

Lumacept teamed up with Sanford Health in Fargo to help design its new Special Care Unit for highly infectious patients. The new unit is equipped with UV fixtures and Lumacept’s UVC-Max coating on the walls and ceiling in order to rapidly disinfect the room. An adjacent anteroom also uses UV to help disinfect healthcare worker’s personal protective equipment (PPE) prior to doffing. The diffuse reflective properties of UVC-Max helps to disperse the UV light and ensure indirectly illuminated areas of the room receive an adequate dose of UV. Lumacept’s LumaSim technology was also used to help design the layout of the light fixtures in both the patient room and anteroom.

You’ve probably never worried too much about it, but humans are incapable of seeing UV light. Because of this, it is impossible for us to see which parts of a hospital room are getting illuminated with UV and which are in shadow. Worse yet, we aren’t even able to use visible brightness as an indicator, since surfaces that look very reflective in visible light might be completely absorbing in UV light.

But thanks to modern CCD camera technology, there actually is a way to essentially “see” UV. Certain cameras are sensitive to UV light, including some which are sensitive down to the UV-C range. These aren’t ordinary cameras, such as what you’d find on a smartphone. Rather, they are specially-designed cameras used for industrial purposes. Here is an interesting link with more information.

By taking a camera sensitive to UV-C and adding filters that block out everything other than UV (visible light, infrared, etc.), we’ve been able to construct a UV-C imaging system that allows us to visualize UV-C absorption and reflectivity. What this approach can produce are monochromatic images in which UV-C absorbing surfaces look dark, while UV-C reflecting surfaces look bright. The degree of brightness is proportional to the intensity of the reflected light. This allows us to demonstrate the reflective properties of Lumacept, and to show how most surfaces in a room absorb UV-C.

Here’s one example.

On the left is a visible image from a hospital room. It shows a bed rail in the foreground and a sharps container and two dispensers mounted on a wall. The image on the right is a UV-C image. The bed rail and other objects are completely black, indicating that they are absorbing UV. In fact, the only surfaces that are reflecting UV are the wall itself, because it was painted with Lumacept, and the metal light switch plate.

So what did that wall look like before it was painted with Lumacept? Here’s a slightly different view of the same wall with the original standard paint. Note that the wooden door also absorbs UV strongly.

This is a UV-C image of Lumacept being brushed onto an absorbing surface consisting of a vinyl wall covering.
If you are familiar with UV disinfection devices, you might have noticed that when a UV lamp turns on, it emits a violet glow. Doesn’t that mean we are seeing UV? The answer is no. Most types of UV light sources, including mercury, amalgam, or xenon lamps, produce some visible light in addition to UV light. The reason for this has to do with the physics of light emission from the gases inside the bulb. So all we are seeing is the small amount of visible light emitted by the lamp. These lamps are usually designed to produce as little visible light as possible, so as not to waste energy on these non-germicidal wavelengths.

Have any technical or not-so-technical questions about UV? We’re happy to help.Contact us atinfo@lumacept.com.

As the use of UV-C disinfection in healthcare facilities continues to grow, infection preventionists are eager to learn more about the technology and how to best implement it in their facilities. It is important not only to understand the basics of how UV light behaves in a hospital room, but also to consider what it means in terms of developing disinfection protocols and designing healthcare facilities.

We like to use this simple graphic to demonstrate the difference between Lumacept and traditional paint.

However, it doesn’t tell the full story. The next time you are in a patient room, look around and notice all of the different materials found throughout the room- on the walls, floor, ceiling, furniture, windows, and equipment. You’ll see a combination of plastics, laminates, wood, glass, metal, ceramic, etc.

So what happens when the UV light from a disinfection device hits these objects? In general, it can only do three things. It can be absorbed, transmitted, or reflected. Usually, it is some combination of the three.

For practical purposes, here is a quick summary of what we can say about common materials found in healthcare facilities:

More about metal: It can be highly UV-C reflective, or it can be only slightly reflective. It really depends on the type of metal and surface quality. Highly polished aluminum is about as reflective as it gets, while dull stainless or galvanized steel is significantly less reflective.

We’ll publish more about this topic in the near future. In the meantime, feel free to contact us with your questions.

A study demonstrating the effectiveness of LumaSim for predicting UV irradiance in healthcare facilities was presented at the APIC 2014 Conference in Anaheim, CA.

The study was conducted in two locations. An initial proof-of-concept study was performed at the University of North Carolina in the same rooms used in previous studies of Lumacept. UV-C irradiance measurements were taken in 10 locations throughout the room. Measurements were taken both with and without the presence of Lumacept-painted walls. A 3D model of the room was constructed and LumaSim was used to predict the intensity of UV-C in these locations. Good agreement was found between the measured and predicted values. Below is a rendering from the 3D model for the room containing UV-reflective walls.

A second, more detailed, study was then conducted at Sanford South University Hospital in Fargo, ND. This study included measurements of 20 high-touch surfaces. In addition, 5 different device locations were studied and the UV-reflectivity of the walls was adjusted by painting the room with various grades of Lumacept. Control measurements were also taken in the room using traditional non-UV-reflective paint. The image below shows the locations of several of these target surfaces (red) and the locations of the device (blue):

The results were as follows:

Over a very wide range of UV intensities, LumaSim demonstrated excellent predictive capabilities. For more details, download the APIC Presentation.

The effect of device location is pronounced. The total time necessary to achieve a targeted dose depended heavily on the location of the surface relative to the location of the device. This highlights the need to select device locations carefully.

The effect of Lumacept was to significantly increase the overall level of UV intensity, especially for surfaces not in direct line of sight of the device. Further, Lumacept greatly reduced the amount of time necessary to achieve a target dose on all surfaces.

Most of the ingredients in normal paints (binders, additives and pigments) absorb the deeper ultraviolet wavelengths in UV-C simply due to their molecular structure. UV-C is a very short wavelength of light that is absorbed by many types of molecules including many carbon bonds present in living things and in polymers and paints. The germicidal properties of UV-C are due to UV-C being absorbed by DNA’s molecular structure, which leads to bond-breaking and DNA errors that render microbes unable to replicate. A typical paint or plastic material will absorb about 95% of light at 254 nanometers (the most common germicidal UV-C wavelength). To develop patent pending Lumacept™ we had to essentially re-write the book on coating formulation, to provide interior latex coatings with high UV-C reflectivity.